Existing methods of producing rf a-mode plasmas at atmospheric pressure rely on either the use of helium as a majority species (more than 50% of the gas composition) or the use of pre-ionizing mechanisms such as electron beam excitation or laser irradiation. When helium is used as a majority gas species, the rarity and the cost of helium make the technology less attractive economically. The use of electron beam excitation or laser irradiation makes the technology difficult and complicated to implement in a wide range of applications. Applications of atmospheric pressure plasmas include, but are not limited to, various semiconductor manufacturing processes, such as photo-resist removal. The plasmas also can be applied to medical and food sterilization, and cleaning of contaminated surfaces.
Accordingly, it is an object of the present invention to make the use of atmospheric pressure rf a-mode plasmas economical and convenient for various applications.
It is another object of the present invention to use less expensive and available gases such as argon and oxygen.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.